September 20, 2022

Is this epoxy coating solvent-free?

There are many different types of epoxy coatings on the market. They vary a lot in application but the chemical reaction upon curing behind these types of coatings all boil down to the same thing; a reaction of an epoxy functional resin with an amine or amide functional hardener. But where exactly is the difference between solvent-based, solvent-free and water-based? We explain...

Roughly speaking, there are three types of common epoxy systems:

  • Solvent based
  • Solvent free
  • Water base (water-based, water dilutable)

Despite the 3 different terms, all three can contain solvent. Even the solvent-free and water-based products. The variation is in the type of solvent and whether this solvent should be counted as a Volatile Organic Compound (VOC).

Today, a solvent is counted as a VOC if its boiling point is below 250°C. Above that, we talk about SVOC (semi volatile organic compounds). These have a higher boiling point than 250°C and are often not noticeable due to the lack of a characteristic solvent odor.

Solvent-based epoxy
The term, of course, says it all. There is indeed a noticeable amount of VOC in the epoxy product. Even before the product cures, this solvent must first evaporate. The function of the solvent is to make the product very fluid (thin) and even so thin that it is also easy to spray. One often still finds this in sprayable epoxy for boats or other industrial applications. Some commercial floor coatings also contain a noticeably small amount of VOCs.

Solvent-free epoxy
Solvent-free epoxy comprises a very large share in the market and especially in flooring application. The epoxy resin itself has the function as a curing resin, but also has the dissolving ability so that it processes well and smoothly. However, this product still often contains reactive thinners and many commercial products also contain benzyl alcohol(see MSDS). Curiously, despite its boiling point of 205°C, benzyl alcohol is often not counted as a VOC. But in reality, this substance does evaporate or migrate slowly from the cured surface. So in many cases, a solvent-free epoxy coating is not solvent-free at all.

Water-based epoxy
The last category involves water-based epoxy. In this type of product, water is what dilutes the product and gives it its flowing properties. After the water has evaporated out, the curing process can get well underway. Also, many water-based epoxy products on the market still contain some degree of VOC or sVOC. This is often called a co-solvent. These are still used so that the epoxy resin can flow properly and obtain the proper compaction. We always recommend looking carefully at the MSDS to find out if it is actually solvent-free. Often you will still find substances such as, methoxy propanol, di-acetone alcohol or 2-butoxyethanol.

EPX Epoxy from Pol Coatings B.V.
It is good to know that our EPX water-based epoxy products do not contain co-solvents and benzyl alcohol. In addition, our epoxy products have been tested for emissions for 30 days after application. These tests resulted in an optimum air quality, allowing us to call our products emission-free in accordance with standard EN 16516.


Written by: Polcoatings

Are you looking for a product for a specific application or want more information?